#include<stdio.h>
#include<math.h>

int main(void)
{
	double x1,x2,y1,y2,z1,z2;
	scanf("%lf %lf %lf",&x1,&y1,&z1);
	scanf("%lf %lf %lf",&x2,&y2,&z2);
	printf("%.3lf",sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)+(z1-z2)*(z1-z2)));
	
	return 0;
}
